1. Field of the Invention
The present invention relates to wire facing units for reinforced earthen retaining walls wherein the face of the retaining wall is formed by a vertically extending section of the wire facing unit and which includes an integral horizontally extending floor that extends rearwardly for securing a polymer geogrid thereto. More particularly, the present invention relates to a combined, unitary connector strut which interconnects and supports the face and floor of the wire facing unit, while at the same time securing a geogrid to the floor, as well as the assembly of retaining walls with the wire facing unit and connector strut, and methods of constructing a retaining wall with such elements.
2. Description of the Related Art
The use of welded wire facing units in the construction of retaining walls is well known as is the use of polymer geogrids to reinforce such earthen formations. See, for example, U.S. Pat. Nos. 4,856,939 and 6,595,726, each of which discloses the construction of a geogrid-reinforced earthen retaining wall incorporating welded wire facing units. Polymer geogrids, particularly uniaxially stretched integral polymer geogrids of the type preferred for use in the construction of such retaining walls, may be made by the process disclosed in U.S. Pat. No. 4,374,798.
The above-referenced '726 patent discloses a wire facing unit having a face section and a floor section, with the floor section including protuberances defining aligned openings adjacent a rear edge of the floor section. The protuberances provide an effective arrangement for receiving the polymer geogrid by the placement of selected geogrid apertures over the protuberances and then inserting a relatively lengthy connecting rod through the aligned openings of the protuberances to retain the geogrid to the floor section. The connecting rod overlies the geogrid and is captured by the protuberances to retain the geogrid from disengagement with the wire facing unit under high stress conditions. In addition, a separate strut element is provided to interconnect the top of the face section with the rearward portion of the floor section, essentially defining a hypotenuse of a triangle, to support the face section with respect to the floor section and to provide strength to the overall wire facing unit. Thus, two separate and distinct elements were required to support the facing unit, as well as to connect or secure the geogrid to the floor of the facing unit.
The retaining wall system of the '726 patent has been commercialized. Although cost effective and successful, multiple steps are required to install the system. One of the first steps is to connect the geogrid to the wire facing unit through the insertion of the connector rod. A separate distinct step requires installation of the separate support struts. In the commercial system, support struts are typically required to be spaced apart no more than 16 inches to maintain proper face alignment in accordance with design guidelines of the American Association of State Highway and Transportation Officials (“AASHTO”). Specifically, such guidelines require that the face structure bulge not exceed two inches.
In addition to requiring separate and distinct connecting rods and strengthening struts, each of which perform different functions, the insertion of the elongated connecting rods is difficult to achieve where the connecting rod has to extend through several aligned openings, particularly where separate and distinct wire facing units lie in a horizontal side-by-side relationship. The connecting rod has to be lengthy, approximately the width of the facing unit because insertion is from an end region and needs to extend to or near the opposite end region. Further, for facing units intermediate the two end units, it is often required that the facing units be tilted for insertion of the connecting rod and frequently requires the connecting rod to be relatively flexible for ease of insertion. This is time consuming and labor intensive.